diff --git a/library/StmContainers/Bimap.hs b/library/StmContainers/Bimap.hs
--- a/library/StmContainers/Bimap.hs
+++ b/library/StmContainers/Bimap.hs
@@ -74,18 +74,19 @@
 -- or update it and return the new value.
 {-# INLINE focusLeft #-}
 focusLeft :: (Eq leftKey, Hashable leftKey, Eq rightKey, Hashable rightKey) => B.Focus rightKey STM result -> leftKey -> Bimap leftKey rightKey -> STM result
-focusLeft valueFocus1 leftKey (Bimap leftMap rightMap) =
+focusLeft rightFocus leftKey (Bimap leftMap rightMap) =
   do 
-    ((output, change), maybeRightKey) <- A.focus (B.extractingInput (B.extractingChange valueFocus1)) leftKey leftMap
+    ((output, change), maybeRightKey) <- A.focus (B.extractingInput (B.extractingChange rightFocus)) leftKey leftMap
     case change of
       B.Leave -> 
         return ()
       B.Remove -> 
-        forM_ maybeRightKey $ \ rightKey -> A.delete rightKey rightMap
-      B.Set newKey2 ->
+        forM_ maybeRightKey $ \ oldRightKey -> A.delete oldRightKey rightMap
+      B.Set newRightKey ->
         do
           forM_ maybeRightKey $ \ rightKey -> A.delete rightKey rightMap
-          A.insert leftKey newKey2 rightMap
+          maybeReplacedLeftKey <- A.focus (B.lookup <* B.insert leftKey) newRightKey rightMap
+          forM_ maybeReplacedLeftKey $ \ replacedLeftKey -> A.delete replacedLeftKey leftMap
     return output
 
 -- |
@@ -118,19 +119,15 @@
 -- Insert the association by the left value.
 {-# INLINE insertLeft #-}
 insertLeft :: (Eq leftKey, Hashable leftKey, Eq rightKey, Hashable rightKey) => rightKey -> leftKey -> Bimap leftKey rightKey -> STM ()
-insertLeft rightKey leftKey (Bimap leftMap rightMap) = 
-  do
-    A.insert rightKey leftKey leftMap
-    A.insert leftKey rightKey rightMap
+insertLeft rightKey =
+  focusLeft (B.insert rightKey)
 
 -- |
 -- Insert the association by the right value.
 {-# INLINE insertRight #-}
 insertRight :: (Eq leftKey, Hashable leftKey, Eq rightKey, Hashable rightKey) => leftKey -> rightKey -> Bimap leftKey rightKey -> STM ()
 insertRight leftKey rightKey (Bimap leftMap rightMap) = 
-  do
-    A.insert leftKey rightKey rightMap
-    A.insert rightKey leftKey leftMap
+  insertLeft leftKey rightKey (Bimap rightMap leftMap)
 
 -- |
 -- Delete the association by the left value.
diff --git a/library/StmContainers/Multimap.hs b/library/StmContainers/Multimap.hs
--- a/library/StmContainers/Multimap.hs
+++ b/library/StmContainers/Multimap.hs
@@ -12,8 +12,8 @@
   deleteByKey,
   reset,
   unfoldlM,
-  unfoldMKeys,
-  unfoldMByKey,
+  unfoldlMKeys,
+  unfoldlMByKey,
   listT,
   listTKeys,
   listTByKey,
@@ -149,14 +149,14 @@
 
 -- |
 -- Stream keys actively.
-unfoldMKeys :: Multimap key value -> UnfoldlM STM key
-unfoldMKeys (Multimap m) =
+unfoldlMKeys :: Multimap key value -> UnfoldlM STM key
+unfoldlMKeys (Multimap m) =
   fmap fst (A.unfoldlM m)
 
 -- |
 -- Stream values by a key actively.
-unfoldMByKey :: (Eq key, Hashable key) => key -> Multimap key value -> UnfoldlM STM value
-unfoldMByKey key (Multimap m) =
+unfoldlMByKey :: (Eq key, Hashable key) => key -> Multimap key value -> UnfoldlM STM value
+unfoldlMByKey key (Multimap m) =
   lift (A.lookup key m) >>= maybe mempty B.unfoldlM
 
 -- |
diff --git a/stm-containers.cabal b/stm-containers.cabal
--- a/stm-containers.cabal
+++ b/stm-containers.cabal
@@ -1,5 +1,5 @@
 name: stm-containers
-version: 1.1.0.2
+version: 1.1.0.3
 synopsis: Containers for STM
 description:
   This library is based on an STM-specialized implementation of
@@ -41,7 +41,7 @@
   build-depends:
     base >=4.9 && <5,
     deferred-folds >=0.9 && <0.10,
-    focus >=1 && <1.1,
+    focus >=1.0.1.3 && <1.1,
     hashable <2,
     list-t >=1.0.1 && <1.1,
     stm-hamt >=1.2 && <1.3,
@@ -54,6 +54,7 @@
   default-language: Haskell2010
   main-is: Main.hs
   other-modules:
+    Main.BimapTests
     Main.MapTests
     Main.MapTests.Update
   build-depends:
@@ -61,6 +62,7 @@
     focus,
     foldl >=1.4 && <2,
     free >=4.6 && <6,
+    list-t,
     HTF ==0.13.*,
     QuickCheck >=2.7 && <3,
     quickcheck-text >=0.1.2.1 && <0.2,
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -4,6 +4,7 @@
 import Prelude
 
 import {-@ HTF_TESTS @-} Main.MapTests
+import {-@ HTF_TESTS @-} Main.BimapTests
 
 
 main = htfMain $ htf_thisModulesTests : htf_importedTests
diff --git a/test/Main/BimapTests.hs b/test/Main/BimapTests.hs
new file mode 100644
--- /dev/null
+++ b/test/Main/BimapTests.hs
@@ -0,0 +1,43 @@
+{-# OPTIONS_GHC -F -pgmF htfpp #-}
+module Main.BimapTests where
+
+import Prelude
+import Test.Framework
+import StmContainers.Bimap
+import qualified Focus
+import qualified ListT
+
+test_construction = do
+  m <- newIO :: IO (Bimap Int Int)
+  atomically $ insertRight 3 1 m
+  atomically $ insertRight 4 2 m
+  assertEqual [(3, 1), (4, 2)] =<< atomically (ListT.toList (listT m))
+
+test_deleteLeft = do
+  m <- newIO :: IO (Bimap Int Int)
+  atomically $ insertRight 3 1 m
+  atomically $ insertRight 4 2 m
+  atomically $ deleteLeft 4 m
+  assertEqual [(3, 1)] =<< atomically (ListT.toList (listT m))
+
+test_deleteRight = do
+  m <- newIO :: IO (Bimap Int Int)
+  atomically $ insertRight 3 1 m
+  atomically $ insertRight 4 2 m
+  atomically $ deleteRight 2 m
+  assertEqual [(3, 1)] =<< atomically (ListT.toList (listT m))
+
+test_replactingConstruction = do
+  m <- newIO :: IO (Bimap Int Int)
+  atomically $ insertRight 3 1 m
+  atomically $ insertRight 4 2 m
+  atomically $ insertRight 3 2 m
+  assertEqual [(3, 2)] =<< atomically (ListT.toList (listT m))
+
+test_insertOverwrites = do
+  m <- newIO :: IO (Bimap Int Int)
+  atomically $ insertRight 3 1 m
+  atomically $ insertRight 3 2 m
+  assertEqual Nothing =<< atomically (lookupRight 1 m)
+  assertEqual (Just 3) =<< atomically (lookupRight 2 m)
+  assertEqual (Just 2) =<< atomically (lookupLeft 3 m)